It has been proposed to provide a technique for detecting a detection object such as a finger which has not yet touched a capacitance sensor based on a change in an electrical charge stored in the capacitance sensor (for example, see Patent Document 1).
The output of the capacitance sensor is dependent on the distance between the capacitance sensor and a detection object as well as the opposite area between the detection object and the capacitance sensor; therefore, it is difficult to determine whether the distance from the detection object is shorter or whether the opposite area between the capacitance sensor and the detection object is larger only based on the amount of an electrical charge stored in the capacitance sensor.
[Patent Document 1] Japanese Patent No. 4766340